Controlling mechanism



L! A'. LANG.

-coNTRoLLlNG 'MECHANISM APPLICATION FILED' JUNE 28.1916.

Patenamay 2, 1922,

3 SHEETS-SHEET l.

y y m//Z a /7 L. A. LANG. CONTROLLING MECHANISM.

APPLICATION FILED IuNE 28, I9I6.

Patented IIIay2,1922.

3 SHEETS-SHEET'Z.

a l /0d gwn@ I To@ L. A. LANG.

CONTHOLLING MECHANISM.

APPLICATION FILED1UNE28.1916.

Patented. May 2, 1922,.'

3 SHEETS-SHEET 3.

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CONTROLLING HECHXNISH.

.applicaticn le June 26,

To all whom it may concern.'

Be it known that i, LINCOLN A. LANG, a citizen of the United States,residing at Chicago, Illinois, have invented certain new and usefulImprovements in Controlling Mechanism, of which the following is aspecication. A

My controlling mechanism is of that class in which power is applied tofmove the controlled member to and fro. The'application of this power isregulated by a hand controlled device of the controlling mechanism andin preferred forms of this apparatus more or less manual power may beapplied to t-he controlled member through the hand operated device.Means are also provided by which movement of the controlled member underpower for a distance appropriate to a certain movement of the handcontrol,- ling member neutralizes the effect of the movement of the handcontrolled member and effects a discontinuance of mdvement of thecontrolled member. Such means may be conveniently described as follow-upmechanism.

The present invention provides improvements in this class of controllingmechanism and the` principal objects of the improvements are to causethe relation of movement of the controlled member to the handcontrolling member to be constant throughout their ranges of movement;to. cause the movement of the controlled member Jto be immediately,delicately and accurately responsive to the movement of the controllingmember and to more effectively lock the controlled member in position orenable it to a certain sort intermediate the hand com' trolling memberthe valve actuating means and the controlled member.

After thorough study of controlling mech- 'A anism of this-gei1eralclass, some of which are known as-servo-motors, I find that'they haveusually some or all of the following characteristics: The controlledmember does not immediately respond to the movemept .Specification ofletters Patent.

Patente@ may e, mea 1916. Serial No. 106,496.

of the controlling member;v the speed or degree of movement, or both ofthese, of the controlled member do not correspond to the movement of thehand controlling member so accurately as could be desired; the normal orintended ratio of movement of the two members is also diderent fordifferent parts o f the range of movement of the controlling member andthe apparatus does not respond so quickly or accurately as could bedesired to prevent dislocations of the controlled member from anintended fixed position. Ihave also discovered that thesecharacteristics are principally, if not entirely, due to the employmentof slide valves to control the motive duid and to the employment in thefollow-up mechanism of a lever or some kind ofdi'erential mechanismwhich does not have sucintly uniform action or is not sufficientlysensitive.

In considering Ways of overcoming these .diculties ll conceived thatpoppet valves would have the quick and responsive action necessary togive the improved results that li desired, and that the follow-upmechanism or that part of the mechanism interacting between the handcontrolling member, controlled member and valves should embody twosimilar or uniformly acting di'erential members, preferably gears, whichshould act upon the variable member of the di'erential group nniformlyinall positions. But poppetvalves are peculiar, in that they are usuallyseated bya spring and are operated by actively moving thenr in only onedirection, and it was necessary-to discover and adapt novel 'valveactuating means and a' nove valve'arrangement, and to adapt to thesefeatures the desired kind of differential mechanism.

After the adaptation of the various parts i alongfthe indicated lines, Ihave demonarran ed an perated for this purpose .by

suitab e operating means; that they'give a substantially immediateresponse to the movementlof the controlling member` and avoid thedifficulties 1 in previous mechanisms due to the overlap of valves, andthat the differential mechanism cooperates properly with the valves toproduce the desired delicacy, speed, accuracy and uniformity of ratio ofmovement of the controlled member to the controlling member, and thatmoreover the ratio of movement of these parts is constant for allpositions of the controlling member.

I-Will now describe one physical embodiment of the invention, and inconnection with this description will further point out -thecharacteristics and advantages of the invention so far as may benecessary. It should be understod that the invention can-be.embodied inmany dierent forms, and I do not limit myself to details except asclaimed hereafter. l

The accompanying drawing shows one exemplifying embodiment of theinvention:

Fig. 1 is a side elevation.

Fig. 2 is a right hand end elevation.

Fig. 3 is a'top plan with the steering Wheel removed.

Fig. 4 is a vertical longitudinal section, the main section plane beingthat of the centres of the two valves at one side of the cylinder.

Fig. 5 is a transverse section through the valves at one end oii thecylinder.

Fig. 6 is a transverse section at the centre of the structure.

Fig. 7 is a horizontal section in a plane just above the rack.

In the present embodiment the invention is adapted tosteering roadvehicles and in such vehicles a convenient motive power is air underpressure, stored in a suitable tank by a pump driven by the vehicleengine. For the sake of brevity, thel exemplifying structure will bedescribed as adapted to automobile steering and air will be referred toas the motive fluid, but, it will be understood that the invention maybe adapted to various other uses such as operating locomotive reversegearing, the elevating mechanism of gun carriages, etc., and that othermotive fluids, such as steam or water or oil under pressure, may be usedin some cases.

The ycylinder l has a piston la whose piston rod 1b is connected bycross pieces 2a to a r'ack bar 2. Thisslides in a` suitable guide 3,which in this embodiment is a part of the cylinder casting. At each end:of the cylinder is an' exhaust poppet valve 19 010s-, ing upon a seatA25 screwed intothe cylinder casting. The stems 19zi of these exhaustvalves pass upward through cages 33 a-nd are guided in upward extensions34 of the cages and protrude above thesey extensions for actuation bysuitable means to be described. IThe valves are held seated by suitablesprings according to ordinary poppet valve construct-ion. The valve seatmem-l bers 25 have perforations 26 to permit discharge of air into thecages 33 and thejcages have perforations 35 to discharge 'the exhaustair to atmosphere. 1.

At. each end of the cylinder is an intake poppet valve 20 closingagainst a seat 25.

'sions 30 at the top of the cages and the upper ends of t'he valvestemslprotrude above the cages as in the case of the exhaust valves.

These intake valves are packed and also have l suitable springs, and thevalve seat members 25 have perforations 26 for the passage of intake airwhen the valves are opened.

'To permit lthe valves to be properly actuated by suitable valveactuating mechanism which I have devised'for the purpose, and to permitair to be properly supplied and exhausted to and from the cylinder bythese valves when so actuated, one intake valve and one exhaust Valveare placed as above described at each end of the cylinder, but thesimilar valves at opposite ends of Ithe cylinder are arranged atopposite sides thereof so that if the cylinder is observed from eitherend, at the end. nearest the observer there is an intake valve 20 at theright* andan exhaust valve 19 at the left,

.while at the further end of the cylinder 'there is an exhaust valve 19at the right and an intake valve 2() at the left. Described otherwise,the similar' valves at opposite ends of the cylinder are diagonallyarranged. This valve arrangement permits airpassages to be convenientlyand satisfactorily arranged as follows: Below each intake valve 20 is asupply chamber'22 to which air under pressure is supplied from a.suitable tank (not shown) through connections 24 in the cylindercasting. From a point above each of the intake valve seats 25 an airpassage '31 leads through the cylinder casting to an air chamber 23below exhaust valve 19 at the opposite end of the cylinder. This air`chamber 23 connects by a port 27 with the adjacent end of the cylinder.If intake valve 20 at one end of the cylinder is open. as shown in Fig.4, air under pressure passes from the supply chamber 22 throughperforations 26 in the valve seat to the cage 29, and from thecagethrough passage 31 to chamber 23 at theV opposite end of thecylinder and from thischamber through the port 27 to the cylinder. Ifthe I'valve 19 above the chamber 23 is closed, as shown in Fig. 4. airis prevented from escaping at' that end of the cylinder. If at the same"time, the

exhaust valve 19 directly behiiid the intake valve 20 in Fig. 4, or atthe left in Fig. 5,

35 in the cageI to atmosphere. If the intakevalve at the opposite end ofthe cylinder,

that is, directly behind the valve 19 as seen in Fig. 4, remainsclosed,- there will: be n0 supply of air to the leftv hand end of thecylinder at this time.A By the simultaneous opening, that is, of anexhaust valve and an intake valve at one'end of the cylinder, air isexhausted from that endl and is supplied to the-opposite' end of thecylinder owing to the arrangement of the air passages, andthe piston ismoved toward -the first mentioned end of the cylinder, and similarly bysimultaneously opening the supply and exhaust valve at the other end ofthe cylinder the piston will be caused to move in the oppositedirection. Suitable' valve actuating means will now be described.

Uprights 3 extending from the cylinder casting carry in suitablebearings a rock shaft 5, and on this is mounted for relative oscillationthe hub 10 of a valve operating member, comprising in connection withthe hub, arms 10"l and 10b each of which carries two adjustable valvetappets 36. The lower end of one of the tappets lies above the upper endof each vave stem so that When the rocker is moved in one direction itstappets 36 depress the stems of an intake and eX- haust valve at thecorresponding end of the cylinder, while' the two valves at the oppositeend are held closely Vby their springs, and similarly opposite movementof the rocker will open the two valves at the other end of the cylinderwhile the two first mentioned are held closed by the springs.`

To enable the valve actuating rocker 10 to be controlled mutually by thehand controlling member and the controlled member of the mechanism,suitable dii'erential gearing, in which is incorporated a suitablefollow-up mechanism, is provided as follows: The rocker hub 10 hasanother arm 9 on which is revolubly mounted a beveled differentialpinion 8. Une side of this pinion engages abevel gear sector 7 b carriedby a hub 7 keyed to shaft 5. This hub also carries a spur gear sector 7aengaging the rack bar 2'previously mentioned. The other side ofdifferential pinion 8 engages a bevel gear 11 of which apart equal insize to the sector 7h constitutes the other member of-a differentialcouple similar to the sector 7b.

' This gear 11 is revolubly mounted onshaft 5 and for convenience has agear of full circumference so that- 1t canl also be engagedby a bevelpinion 12 carried on controllingl shaft 13 vrevolubly mounted insuitable bearings 14, and carrying'at its upper end the hand controllingmember, in this instance a hand wheel H. It will be evident that thegear-1 member 11 might be simply a sector similar to the sector 7h andmight be operated bv placing ahandle directly upon its hub. The :presentarrangement is to adapt the controlling vmechanism to conditions usuallyfoundin automobiles.

Rigidly ixedfon'shaft 5is an arm 6 which constitutes the controlledmember of 'the mechanism. This is to be connected in angll e5,

suitable Way to the member to be operate In this instance,vthe'arm is tobe connected directly to the usual drag link of the steering wheels ofan automobile.

The operation is as follows: AWhen the hand controlling member H isrotated in either direction so that the steering shaft 13 rotates in thedirection of the arrow, Fig. 6, the movement of steering arm 6 ismomentarily resisted by its connection with the steering wheels of thevehicle, and the bevel sector 7b connected-iigidly with this arm thusacts momentarily as an abutment. The rotation of bevel pinion 12 carriedby the steering shaft rotates bevel gear 11, and this causes rotation ofbevel pinion 8 upon its axis. The engagement of the pinion with the gear7b, now stationary, causes the rocker 10 to oscillate upon shaft 5 insuch a direcT tion that the arm 10b is depressed and eX- haust valve .19and intake valve 20l at the rack bar 2 is similarly moved; thisvbar be-Aing in engagement with spur sector 7a causes the controlled member 6 tomove to the left in Fig. 1 or toward the observers'eye in Fig. 6, andthe steering Wheels of the vehicle are deflected correspondingly. Bevelgear sector 7b moves in correspondence with the movement of thecontrolled member 6 and causes a` compensating movement of the bevelpinion '8, or, in other Words, causes the pinion tohave a follow-upmovement so that substantially as soon as movement of the handcontrolling member ceases the gear 11 acts as an abutment and movement.of

gear sector 7b restores pinion 8 to its normal position, bringingtherocker 10 backto intermediate position and causing the two valves at theleft end of the cylinder to be closed, whereupon the controlled member 6is promptly stopped and so held. nOpposite .movement ofthe hand Wheelwill cause opposite-moveinent of thexcontrolled member in-an obviousway. The mechanism hasa'n inherent capacity to resist and compensate foroutside disturbances which tend to move the controlled member 6. Forinstance, sup* pose that road shock causes a defiection of the steeringWheels of the car, which tends' to movejthe arm 6 to the left in Fig..1,or

towardv the observers eye in Fig. '6, This L movement will at once becommunicated through shaft 5 tothe spur sector 7,i and so through therack bar 2 and pistonrod 1b to the piston; the piston is to a certainextent locked by the fluid pressure in the cylmder and movement of thearm 6 is at first resisted by these means. f But if the arm moves to anyappreciable extent th'e gear sector 7b is correspondingly moved; thehandwheel H being lightly held by the driver-or even remaining stationary byitsoWn inertia, or

. rocker is depressed and the valves at the right hand end of thecylinder in Fig. 4 are opened; this causes movement of the piston to theright in Fig. 4 sufficiently to compensate for the disturbance ofcontrolled member 6 and lto keep it in substantially fixed positionwithout the attention of the operator or without any appreciablephysical exertion.

In addition to the automatic power control and follow-up capacity nismdescribed, it'has the additional advantage that manual effort applied tothe hand controlling member may be communicated tothe controlled memberin proportion to any partial or complete failure of the power means, orto any extent desired, if the power means is partly or entirelyeliminated by intention; and this application of manual effort to thecontrolled member may be instantaneously made without conscious thoughtof the operator and with.- out manipulating any part of the mechanismexcept thehand controlling member itself. Moreover, the movement of thehand controlling Amember at any' stated speed and for any stateddistance will lcause the same movement of the controlled member, whetherthat movement is accom plished entirely by the manual effort of theoperator or entirely by power or by any combination of the two. When thehand wheel H is moved a short distance iii either direction, if themotive fluid does'not act with great promptness to move the controlledmember and so to restore the rocker 10 to normal position, or tocompensate for the movement of the hand wheel, thev said slight movementof the hand wheel lacts through the differential mechanism to move therocker l0 to the limit of its travel in either direction, that is tocause one of the rocker armsto engage with its stop 37. Thereupon, therocker serves as anabutment for the transmission of manual effort frombevel pinion 12, through gear 11, to pinion 8, and the gear sector 7b isthus moved in the fappropriate direction. and the controlled member 6 isalso moved in the proper direction. The manual effort required for themovementjof the controlled member will evidently be in proportion to ofthe mechathe failureof the power means, because the valves are actuatedin the described movementuof the hand wheel, and the power means willact to move the controlled member u to its capacity.

Di erent adjustments of the valve actuatingmeans may be made to producement of the mechanism the tappets 36 are S adjusted that when the rocker10 is in intermediate position the intake valve tappets have 'noclearance from the stems of the intake valves and the intake valves arebarely closed, or even very slightly opened, or, to use descriptivelanguage, just fluttering on their seats, while there is a very slightclearance between the exhaust valve tappets and the exhaust valve stems.In this way there is always pressure in each end of the cylinder tendingto hold the piston effectively balanced, and upon the slightest movementof the rocker in either direction one of the intake valves isimmedfately firmly seated while the appropriate exhaust valve is openedand the other intake valve is fully opened and fluid is thus freelyexhausted from one end of the cylinder and supplied to the other and thepiston is promptly moved a distance proportionate to the movement of thehand wheel. The employment of. poppet valves is of great importance inth1s meeha'nism because they 'give an immediate response to the movementof the hand controlling member without any delay or uncertainty ofaction due to the necessary overlap in slide valves. The differentialgearing employed is also such that in any of the positions of thegearing a stated movement of the hand wheel, either as to distance orspeed, will cause thersame movement of the controlled member. This isbecause the differ- :different results, but in a preferred adjustentialgear sectors 7a and 1l are exactly similar, and are, moreover, ofuniform sha e Iand act uniformly -upon the differentlal pinion 8 in allpositions. `VThere is, therefore, no luncertainty in the compensationafforded by the mechanism or in the capacity of the machinetoautomatically resist outside disturbances, such as is the case incontrolling mechanism employin compensating levers or other deviceswh1ch do not have a uniform action in all their positions.

-prompt and immediately' effective as rtheir opening movement,0thecontrolled member practically impossible'to cause the rocker' toencounter its fixed stops if any considerable latitude of movement' ispermitted by the stops, for'the reason that the controlled I memberfollows the action of the hand controlling member so promptly that thehand controlling member can hardly be moved quickly enough to cause anyvery great considerable depression of the valve operating rocker ineither direction. The clearance afforded by the stops 37 may, therefore,vbe

lvery slight and such that if the power means fails partially orwhollyat any time, this clearance will be taken' up by anfalmost imperceptiblemovement of the controlling member and therewill, therefore, be noperceptible or objectionable delay in the application of manual power tothe controlled member, because -the rocker 10 will 4substantiallyimmediately encounter one of the stops 37 and act as an abutment for theconveyance of manual power'to the controlled member.

vlclaimzl 1. Ina servo-motor, the combination of a hand-controllingmember, a member controlled thereby and movable by power, Huid pressuremechanism for lmoving said controlledmember to and fro, and valvemechanismfor delive-rin and discharging fluid to and -from saidluld-operating mechanism,

said valve mechanism being mechanically connected to both of saidmembers and arranged to be Aactuated by movement of either of saidmembers relative to the other, and including a pair of inlet poppetvalves adapted to open alternately upon actuation of said valvemechanism in opposite directions, at least one of said valves alwaysbeing open, and a pair of poppet exhaust valves also alternatelyoperable by opposite movements of said valve-actuating mechanism, andadapted toremain closed contemporaneously during a'substantial movementof said controlled member.

2. lIn a servo-motor, the combination of a lhand controlling member, amember controlled thereby and movable by power, fluid pressure mechanismfor moving 'said controlled member to and fro, and valve mechanismvcomprising inlet valves and exhaust poppet valves and valve actuating.me lns connected with the controlling member :nd the controlled member,said valves and valve actuating means being constructed and arranged'sothat at least one of the inlet valves is always open, and so that. thevalve actuating means may move considerably `to actuate the inlet valveswhile the exhaust valves remain closed. l

3. -In controlling .mechanism of the class described, the combinationof. a cylinder, a

piston, inlet poppet valves and exhaust poppet valves to control theflow of expansive fluid to and from opposite ends of the cylinder, ahand controlling member, and differential mechanism intermediate thepiston,

valves and hand member, said mechanism comprising a gear operated by thehand member, another gear operated bythe piston,

and a differential pinion actuated by said gears, said ypinion beingconnected with the valves. Y

LINCOLN A. LANG.

